Blank Mask Laminate Ion Control for Haze-Free Exposure
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Solution Overview
Problem
The miniaturization of semiconductor device circuit patterns requires effective suppression of defects during the manufacturing process of blank masks, particularly due to residual ions such as sulfate, nitric oxide, ammonium, and chlorine ions, which cause haze and undesired pattern transcription during exposure.
Innovation Solution
A laminate for a blank mask is developed with a phase shift film composed of molybdenum and silicon, treated with nitrogen to control residual ions within specific concentration ranges (0 ng/cm2 to 5 ng/cm2) and cleaned using UV ozone and hydrogen water to reduce defects, thereby suppressing haze and defects during exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional manufacturing processes are used for blank masks, then production efficiency is maintained, but residual ions (sulfate, nitric oxide, ammonium, chlorine) cause haze and defects during exposure
Solution Approach 1:
The patent applies preliminary action by performing nitrogen treatment during the sputtering process to control residual ions before they can cause haze or defects. The nitrogen atmosphere is introduced during film formation to suppress ion generation, and thermal treatment is performed before final cleaning to remove ions in advance, ensuring high-quality exposure results without requiring excessive post-processing
Solution Approach 2:
The patent employs parameter changes by optimizing multiple process parameters: nitrogen concentration (30-70 volume %) during sputtering, thermal treatment temperature (300-500°C) and time (10-120 minutes), and cleaning solution compositions. These parameter optimizations control residual ion concentrations to specific ranges (sulfate: 0-0.05 ng/cm², nitric oxide: 0-0.5 ng/cm², ammonium: 0-5 ng/cm², chlorine: 0.05 ng/cm² or less), directly improving exposure quality while minimizing harmful ions
2Object-generated harmful factors
If nitrogen treatment is applied during phase shift film formation, then residual ion concentration is reduced, but process complexity increases
Solution Approach 1:
The patent merges the nitrogen treatment step with the existing sputtering process for phase shift film formation. The nitrogen atmosphere is introduced during the same chamber operation where the phase shift film is deposited, combining ion suppression with film formation in one integrated process rather than requiring separate treatment steps, thus reducing overall process complexity
Solution Approach 2:
The patent uses an inert nitrogen atmosphere during sputtering to suppress the generation of residual ions. The nitrogen environment prevents oxidation and ion formation during film deposition, providing a controlled environment that reduces harmful ions without requiring complex additional equipment or multiple processing stages
3Reliability
If multiple cleaning processes are applied to reduce residual ions, then exposure quality improves, but manufacturing time increases
Solution Approach 1:
The patent performs thermal treatment before the final cleaning process to remove residual ions in advance. This preliminary thermal processing reduces the ion load before UV ozone and hydrogen peroxide cleaning, making the subsequent cleaning steps more efficient and reducing the total time required to achieve the target ion concentration levels
Solution Approach 2:
The patent implements a continuous multi-stage cleaning process where UV ozone treatment, hydrogen peroxide cleaning, and rinsing are performed in sequence without interruption. Each stage builds on the previous one, continuously removing ions until the target concentrations are achieved, optimizing the balance between thorough cleaning and manufacturing time
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The laminate effectively reduces residual ions, minimizing defects and improving resolution by controlling ion concentrations, ensuring high-quality semi-manufactured goods and finished products.
Implementation Method 1
the phase shift film or a shading film formed on the light-transmitting substrate... Controlling factors causing haze during exposure of a blank mask
Implementation Method 2
The cleaning of the thermally treated phase shift film includes a first cleaning process of adding UV rays and ozone water to the thermally treated phase shift film
Implementation Method 3
thermally treating the phase shift film... The cleaning of the thermally treated phase shift film includes a first cleaning process of adding UV rays and ozone water to the thermally treated phase shift film
Data Source
AI summary
A laminate for a blank mask includes a light-transmitting layer; a phase shift film disposed on the light-transmitting layer; and residual ions measured from a surface of the phase shift film through ion chromatography comprises at least one of sulfate ions in a concentration of 0 ng/cm2 to 0.05 ng/cm2, nitric oxide ions in a concentration of 0 ng/cm2 to 0.5 ng/cm2, or ammonium ions in a concentration of 0 ng/cm2 to 5 ng/cm2, or any combination thereof. A sum of concentrations of the residual ions is more than 0.